Field of Invention
The present invention relates to production precision molding including encapsulation of an object in plastic such as a semiconductor and in partiar to an insertable aperture molding method and device utilizing a pair of multiple material removable ferrous carrier plates having mating window openings with pre-molded mating pairs of non-ferrous pre-molded inserts each having at least one mold cavity, each having a rubberized retainer ring tension fit in a continuous edge groove surrounding each pre-molded insert which is adapted to be inserted in one of the pair of mating window openings with the retainer ring snapping into a recessed edge groove surrounding the window opening to create three axis floating molds which are insertable, removable, and replaceable in the carrier plates used in a precision production molding process which may include encapsulation molding.
Description of Related Art including information disclosed under 37 CFR 1.97-1.98
Within the field of semiconductor encapsulation there are generally two types of prior art molds. There referred to as Conventional Molds and Plate Molds. Within both prior art molds, the plastic material is directed through long runners and intersecting gates connecting to the cavities, the material flows through these long runners, and gates filling the mold cavities and forming the package to its final shape.
The first of the prior art are Conventional Molds, which are still in use today. Although extremely expensive, it does the job well. But nevertheless there are drawbacks. They are relatively easy to damage, and extremely time consuming when cleaning after the encapsulation cycle; this is because of their design. Repairing a damaged prior art conventional mold device costs considerable time and money.
The second prior art method of encapsulation is known as Plate Molds. This design was a big step forward. Through this prior art method volume increased per encapsulation cycle in encapsulation molding, and easier cleaning was achieved. But it has drawbacks as well. Once the plate Mold design is damaged or worn-out, it cannot be repaired. It is necessary to replace it. The damaged or worn-out plate in most cases is the top plate. In both prior art designs, the gates are subjected to extreme wear. The runner system in the plate mold design is the only item that can be repaired.
Both of the prior art examples (Conventional and Plate Molds) are constructed entirely of ferrous materials which adds cost to these types of mold tools.
U.S. Pat. No. 4,513,942, issued Apr. 30, 1985 to Creasman, indicates an apparatus for encapsulating objects in molded plastic packages, in which an improved removable cavity plate assembly comprises upper and lower cavity plates which fit together in an interlocking manner to define molding cavities having integral surfaces formed within a single cavity plate on all sides of the cavity but one. The fourth side of each cavity is defined by a surface formed by the interlocking juncture between the two cavity plates. Plastic packages molded in the cavities thus are formed without a seam or parting line along the sides formed on the integral molding surfaces, the seam or parting line being formed only on the surface defined by the juncture of the two cavity plates.
U.S. Pat. No. 4,368,168 issued Jan. 11, 1983 U.S. Pat. No. 4,442,056 issued to Slepcevic, puts forth a method for encapsulating electrical components wherein a cavity plate means is removably positioned between upper and lower mold plates with the upper surface of the cavity plate means flush against the upper mold plate. The cavity plate means has openings from top to bottom thereof and holds objects spaced from the upper mold plate with the portions of the objects which are to be encapsulated being in registration with the cavity plate openings. Fluid plastic is forced laterally through feed runners formed in the surface of the upper mold plate and downwardly through gates into the cavity plate openings. After the plastic has hardened, the plastic ejected from the feed runners of the upper mold plate and the cavity plate means is removed. Preferably the objects are pre-mounted on the cavity plate means, and the lower cavity plate surface is positioned flush against the lower mold plate which is uninterruptedly flat. Alternatively, the cavity plate means holds the objects against the lower mold plate which has cavities in registration with the openings through the cavity plate means.
U.S. Pat. No. 4,442,056 issued Apr. 10, 1984 to Slepcevic, is for a molding apparatus having first and second opposed mold surfaces with the first mold surface having a feed runner network. A mold structure is supported by the second mold surface and is spaced from the first mold surface. The mold structure is adapted to hold a lead frame strip and objects held thereby in a plurality of openings. A gate plate fits between the first mold surface and the mold structure. The gate plate has a plurality of gates or apertures from a first to a second outfacing surface portion thereof. Set feed runners can be removed from the molding apparatus by motivating the gate plate laterally across the mold structure. The runners are generally removed from the gate plate by bending the gate plate over a cylindrical surface of small enough radius so that the set runners cannot follow and are forced to separate gradually from the gate plate, eventually becoming completely free and falling away from the molding apparatus.
U.S. Pat. No. 4,480,975, issued Nov. 6, 1984 to Plummer, describes an apparatus for encapsulating electronic components in plastic including a press with upper and lower press members, upper and lower flat plastic carrier plates, and transfer injection means. The plates form a closed cavity and support the electronic component.
U.S. Pat. No. 4,449,690, issued May 22, 1984 to Schroeder, is for an apparatus and a method of use thereof for cast encapsulation of items, particularly electronic components. The apparatus consists of a plurality of identically shaped split matrix elements. Each matrix element has a first surface for receiving and securing the item to be encapsulated. A second surface of another identically shaped matrix element, located on a side thereof opposite to its first surface, is then mated with the first surface securing the item. Thus mated, the first and second surfaces establish a molding cavity for enclosing the item and an orifice providing access thereto. This process of securing an item to a first surface and enclosing it with a second surface is repeated thereby assembling a stack of matrix elements. This stack is then rigidly secured and the molding cavities are filled with particulate filler material through upright orifices. Excess filler is removed by quickly turning the stack over and then righting it again. The stack of matrices is then heated, its orifices filled with a quantity of heated, liquid thermosetting encapsulating compound and exposed to vacuum whereby substantially all air is drawn from the molding cavities through the liquid encapsulating compound. The stack is then again exposed to atmospheric pressure forcing the encapsulating compound throughout the unoccupied voids in the molding cavities after which that compound is permitted to solidify, thereby completing the encapsulation process.
U.S. Pat. No. 4,560,138, issued Dec. 24, 1985 to dePuglia et al, discloses an encapsulation mold having slanted support walls which accommodate a plurality of units that are to be encapsulated, and a runner system for effectively distributing plastic to chamber adjacent the areas of the units that are to be encapsulated.
What is needed is a replaceable mold device and method installing replaceable mating floating non-ferrous molds in re-used mating ferrous carrier plates to overcome the inefficiencies of the two prior art mold types in savings of time and money.